Multi-channel pipettes comprise a plurality of channels, into which liquid is sucked and from which it is simultaneously removed.
Multi-channel pipettes have been manufactured especially for devices called micro-titration plates, comprising 9 mm spaced 8.times.12 wells in a matrix. Multi-channel pipettes used alongside a microtitration plate usually comprise 8 or 12 channel, enabling liquid to be dispensed or removed in a single operation over an entire vertical or horizontal row. Also 4-channel pipettes have been used. FI patent specification 52025, for instance, discloses certain multi-channel pipettes. The sets of cylinders in currently used multi-channel pipettes are made in one piece by injection moulding from plastic.
In pipettes called step pipettes, the liquid absorbed into the container is removed in several small steps. Multi-channel step pipettes used together with microtitration plates are also known. These pipettes involve the problem of an awkwardly long piston stroke to allow for sufficient suction volume. Elliptic cylinder have been used with a view to shorten the piston stroke, as described in FI patent specification 73368. In elliptic pipette cylinders, sealing involves a problem.